best, if it could work in a pistol action would be a .223 steel core FMJ with a sabot in the 45 ACP. or you dublicate the old THV bullet which was also made for the 45 ACP once
http://www.quarry.nildram.co.uk/THV.htm

"

.45 "auto pistol" 3.9 g / 60 grains 620 ms / 2,034 fps 750 j / 553 ft lbs

"When tested by the French police, the bullets worked as advertised in that they could punch through steel plates (XC 18 50 daN steel) while producing wide wound channels with relatively little penetration in Plastiline targets. Specific terminal ballistic data was as follows:

PENETRATION OF STEEL PLATE 3 mm / 0.12 inch"

I think every bullet maker with a CNC lathe can make this bullets today.

the russian go another way with their 9mm Parabellum AP load:
"Perhaps the most interesting recent development has been the Russian adoption of the 9 x 19 round, just as NATO was searching for its replacement. In this case, the 9 x 19 is seen as significantly more effective than the long-established 9 x 18 Makarov (an attempt to boost the performance of the Makarov round up to NATO 9 x 19 levels with the 7N16 high-pressure loading was abandoned because of the danger of using this in older guns). The effectiveness of the new Russian 9 x 19 is significantly enhanced by the development of new loadings which combine the ability to pierce body armour with the benefits of a full-calibre bullet against unprotected personnel. It achieves this by means of a method of construction which is similar to that of Second World War APCR, HVAP and PzGr 40 anti-tank gun projectiles: the bullet has a hard sub-calibre core contained within an outer sleeve and separated from it by a polyethylene layer.

If the bullet strikes an unarmoured target, it holds together to produce a wide wound channel. On impact with armour, the sleeve is stripped away and the core penetrates alone. Two different loadings have been introduced: the 7N21 (5.3 g at 460 m/s for 560 J muzzle energy) and the 7N31 (4.2 g at 600 m/s for 756 J - both figures are from pistol barrels). The latter in particular is a very high-pressure loading which can only be used in particularly strong pistols. Not satisfied with improving the 9 x 19 in this way, the Russians have also introduced a longer 9 x 21 round for special forces weapons to achieve the same effect. The 7N29 AP loading fires a 6.7 g bullet at 410 m/s for 560 J, and will reportedly penetrate two 1.2 mm titanium plates plus 30

layers of Kevlar at 50 m. This Russian approach appears to provide the best of both worlds. The disadvantage is that high impact velocity is needed for this to work, so the bullets (especially in the 9 x 19) are relatively light to maximise the muzzle velocity. This does mean that they will lose velocity relatively quickly, limiting their effective range.

Russian 9mm composite AP bullet, showing the penetrating core and the remains of the sleeve after hitting armour"

http://www.quarry.nildram.co.uk/PDWs.htm